Perhaps there is a USB memory limit, that restricts higher memory capacity working correctly.

There might be a problem with the memory stick formatting - the Cactus User Manual states compatibility only with USB memory sticks with FAT32 formatting, but this may not be what you have.
Can you check what the formatting is for your stick?

After a bit of research, I know how to check formatting. I put this in my laptop, checked out the properties and under the general tab file system states FAT32. So I am now sure that this is compatible with what is required